Shutterfly provides its customers with many coupons. I use them mainly for printing pictures, but have used their service for party invitations and Christmas cards. I prepay for my pictures to get the best deal ($.09 ea). Today I had a coupon for $20 (very generous) and really didn't "need" anything so I printed some generic cards to use for Thank you's, etc.
I LOVE how they turned out and can't wait to receive them in the mail.